1,721,048 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Exploring islands of stability in the design space of cylindrical shell structures
Get PDFThe structural stability of a simple benchmark problem – the snap through of a shallow cylindrical roof – is revisited. The problem is analysed in a robust manner using a technique known as generalised path-following, which combines the mathematical domains of finite element analysis and numerical continuation.Using this technique, the well-known arc-length method for tracing equilibrium paths in load-displacement space is extended to explore other interesting paths on a two-dimensional solution manifold in three-dimensional load-displacement-parameter space. These paths include unconventional equilibrium paths traced by varying a model parameter, e.g. shell thickness, as well as critical paths that describe points where the tangential stiffness matrix is singular – that is where buckling, snap-through or other instabilities occur. For the chosen benchmark problem, a localised region of stable equilibrium exists on one of the unstable equilibrium branches. The evolution of this stable region with variations in shell thickness is explored by tracing the locus of criticallimit points that separate the stable and unstable portions of the equilibrium curve. Hence, without resorting to computationally expensive parametric studies, we establish a two-dimensional manifold of stable equilibria in displacement-load-thickness space, which can be graphically interpreted as an island of stability
High-fidelity design methods to determine knockdown factors for the buckling load of axially loaded composite cylindrical shells
Get PDFThe design of thin-walled structures still relies on empirical guidelines like the NASA SP-8007 for cylinders up till now. This lower-bound guideline does not include important mechanical properties of laminated composite materials, such as the stacking sequence. New design approaches that allow taking full advantage of composite materials are therefore required.
Within this paper newly developed innovative design approaches for axially loaded cylindrical shells are pre-sented and validated by means of high-fidelity buckling experiments of unstiffened composite cylinders. The considered composite shells were designed, manufactured and tested at the German Aerospace Center (DLR) in Braunschweig. The results show that the buckling load can be determined very accurately in contrast to the previous methodology
Exploring islands of stability in the design space of cylindrical shell structures
Get PDFThe structural stability of a simple benchmark problem – the snap through of a shallow cylindrical roof – is revisited. The problem is analysed in a robust manner using a technique known as generalised path-following, which combines the mathematical domains of finite element analysis and numerical continuation.Using this technique, the well-known arc-length method for tracing equilibrium paths in load-displacement space is extended to explore other interesting paths on a two-dimensional solution manifold in three-dimensional load-displacement-parameter space. These paths include unconventional equilibrium paths traced by varying a model parameter, e.g. shell thickness, as well as critical paths that describe points where the tangential stiffness matrix is singular – that is where buckling, snap-through or other instabilities occur. For the chosen benchmark problem, a localised region of stable equilibrium exists on one of the unstable equilibrium branches. The evolution of this stable region with variations in shell thickness is explored by tracing the locus of criticallimit points that separate the stable and unstable portions of the equilibrium curve. Hence, without resorting to computationally expensive parametric studies, we establish a two-dimensional manifold of stable equilibria in displacement-load-thickness space, which can be graphically interpreted as an island of stability
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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